is the place where the result will be copied (may be null).
size_t * result_size
should hold the size of the result. The actual size
of the returned result will also be copied there.
DESCRIPTION
This function will calculate a fingerprint (actually a hash), of
the given data. The result is not printable data. You should
convert it to hex, or to something else printable.
This is the usual way to calculate a fingerprint of an X.509 DER
encoded certificate. Note however that the fingerprint of an
OpenPGP is not just a hash and cannot be calculated with this
function.
RETURNS
On success, GNUTLS_E_SUCCESS (0) is returned, otherwise
an error code is returned.